poor runniing excavator

[Anonymous-0]

I'm running an el 180 cat. runs great for about 40 minutes then starts losing power and running rough. checked suction lines and changed hand primer and transfer pump and filters. runs good again after it cools off. any help would be appreciated

 

[Anonymous-0]

could be the tank breather plugged, or maybe there is wear in the pump so when the fuel is hot and thiner it dosent build up enough pressure for
the injectors to atomise the fuel under compression...